After a long period of time, black carbon soot can build up on the piston rings, cylinder head, valves, and cylinder wall of your engine as a by-product of combustion. This can impact the overall performance of your engine by leading to engine knocking, increased oil consumption, and overheating.
Using unleaded gasoline for your marine engine can reduce the build-up of carbon, but in order to keep your engine in good condition, you still need to remove the cylinder after every 100 hours of use and scrape off the hardened carbon using a solvent and a number of tools.
How to remove carbon build-up
1) When you’re removing the carbon build-up from your engine, it’s important to wear solvent-proof gloves and protective eyewear as it can be irritating to your skin. Once you’re wearing the appropriate protective gear, remove the components of your engine so that you can access the cylinder head.
2) Use a plastic or wooden scraper to remove the carbon away from the head of the cylinder, but be careful not to dig the scraper too deep into the aluminum. For more stubborn carbon deposits, use a wire brush, steel wool or a putty knife to carefully scrape away the excess.
3) Use a solvent that will not damage plastic or aluminum to clean away the remaining carbon and use steel wool to smooth out rougher areas. If necessary, you can also soak the metal components for up to 15 minutes to remove more stubborn deposits.
4) Use the same method to remove the deposits of carbon from the end of the cylinder and the piston. Open each valve by turning the crankshaft and remove any carbon from the valve seats and valves by using a brass wire brush, but make sure that you prevent any grit from falling between the cylinder wall and piston or into the valve chambers.